1. Field of the Invention
The present invention relates to a semiconductor circuit and; more particularly, to a semiconductor circuit having a floating detection circuit which detects the floating state of an input node to which a DC signal is input.
Korean Patent Application No. 93-590 is incorporated by reference herein for all purposes.
2. Discussion of Related Art
A "floating" state is one where no signal is applied to the input node of a device, e.g., where neither a logic "high" nor logic "low," exists. If no signal is applied to the input node, the level detected at the input node is determined according to the specific environmental condition of the internal circuitry. In other words, while the input node is actually in the floating state, the state of the input node may be determined to be either a logic "high" or a logic "low" depending on the internal circuitry, and as a result, the semiconductor circuit may malfunction so as to cause problems in the entire system, including such a semiconductor circuit. Specifically, for semiconductor circuits having high input impedance typically greater than 10 M.OMEGA., such as in analog-to-digital converters which convert analog input voltages into digital representations of the voltage, significant levels of noise can appear in the output even when the signal applied to the input node contains very low noise levels. Therefore, it is necessary that such a semiconductor circuit should be controlled depending on the state of the input node.